SPF is an e-mail anti-forgery technology the enables domain owners to list, in the Domain Name Service (DNS), authorized sources of mail from their domains. It enables mail receivers to reject mail that does not come from authorized sources. This guide describes the second part of the protocol, rejecting mail from unauthorized sources. It assumes you have your Postfix set up and running. Setting up and running Postfix is described elsewhere in the wiki and in the Postfix documentation.
2) Install SPF.
# cd /usr/ports/mail/postfix-policyd-spf-perl/
# make install clean
3) Postfix Integration
There are a number of changes the need to be made to integrate SPF checking with Postfix.
3.1 Enabling the Policy Service
policy-spf_time_limit = 3600s
policy-spf unix – n n – – spawn
3.2 Reload Postfix
3.3 Verifying It’s Working
#tail -f /var/log/mail.log